The crushed glass snow is ideal for these kinds of projects, since you can make the snow any consistency that you need... more melted, more icy, or more like a powder. It also has a slightly transparent, crystallized appearance when you place a bit of it on clothing or helmets.

This is also another interesting exercise in muted colors and limited palettes. It is very essential to keep all the colors more in the cooler range, and very grayed down... even skin tones!